MPO and vasculitis: This drug is used as aveterinary anthelmintic and as an immunomodulator in rheumatoid arthritis.Levamisole has been associated with ANCA vasculitis and pauci-immune RPGN.Serological analysis shows positivity for ANCA in 85% of the patients, withperinuclear pattern (p-ANCA) in 93%, and mixed p-ANCA and cytoplasmic (c-ANCA)patterns in 7%; 57% had antibodies against both myeloperoxidase (anti-MPO) andproteinase 3 (anti-PR3), and 43% had anti-MPO alone8.